util: add create_as() helper

2 files changed, 19 insertions, 10 deletions

diff --git a/src/runner/runc/run.rs b/src/runner/runc/run.rs
index 0735128..39adbc1 100644
--- a/src/runner/runc/run.rs
+++ b/src/runner/runc/run.rs
@@ -1,5 +1,5 @@
 use std::{
-	fs::{DirBuilder, File},
+	fs::DirBuilder,
 	io,
 	path::{Path, PathBuf},
 	process,
@@ -68,15 +68,11 @@ fn output_filename(task: TaskRef) -> PathBuf {
 }
 
 fn collect_output(task: TaskRef, task_def: Task) -> Result<(), io::Error> {
-	// Temporarily switch to the user running Rebel to get the right
-	// owner for the tar files
-	let file = {
-		let _setegid = util::setegid(unshare::BUILD_GID)?;
-		let _seteuid = util::seteuid(unshare::BUILD_UID)?;
-
-		File::create(output_filename(task))?
-	};
-
+	let file = util::create_as(
+		output_filename(task),
+		Some(unshare::BUILD_UID),
+		Some(unshare::BUILD_GID),
+	)?;
 	util::tar::pack(file, "build/tmp/runc/workdir", task_def.output.iter())?.sync_all()
 }
 
diff --git a/src/util.rs b/src/util.rs
index d388a59..460f735 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,7 +1,9 @@
 pub mod tar;
 
 use std::{
+	fs::File,
 	io::{Error, ErrorKind, Result},
+	path::Path,
 	process::ExitStatus,
 	result,
 };
@@ -96,3 +98,14 @@ pub fn setegid(gid: unistd::Gid) -> Result<SetEGID> {
 	unistd::setegid(gid).to_io_result()?;
 	Ok(SetEGID(old_gid))
 }
+
+pub fn create_as<P: AsRef<Path>>(
+	path: P,
+	uid: Option<unistd::Uid>,
+	gid: Option<unistd::Gid>,
+) -> Result<File> {
+	let _setegid = gid.map(setegid).transpose()?;
+	let _seteuid = uid.map(seteuid).transpose()?;
+
+	File::create(path)
+}